/*
 * JaLingo, http://jalingo.sourceforge.net/
 *
 * Copyright (c) 2002-2006 Oleksandr Shyshko
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package ja.lingo.application.util.misc;

import ja.centre.util.assertions.Arguments;
import ja.centre.util.regex.IReplacer;
import ja.centre.util.regex.Replacers;

public class Strings {
    private static final int MAX_LENGTH = 64;
    private static final String MAX_LENGTH_SUFFIX = "...";

    private static IReplacer[] escapeHtmlReplacers = {
            Replacers.plain("&", "&amp;", "&"),
            Replacers.plain("\"", "&quot;", "\""),
            Replacers.plain("<", "&lt;", "<"),
            Replacers.plain(">", "&gt;", ">")
    };
    private static IReplacer[] unescapeSqlReplacsers = {
            Replacers.plain("\\'", "'", "\\'"),
            Replacers.plain("\\\"", "\"", "\\\""),
            Replacers.plain("\\n", "\n", "\\n")
    };


    // Taken from http://www.merriampark.com/ldjava.htm
    public static int getLevenshteinDistance(String s, String t) {
        if (s == null || t == null) {
            throw Arguments.doThrow("Strings must not be null");
        }

        int n = s.length();// length of s
        int m = t.length();// length of t

        if (n == 0) {
            return m;
        } else if (m == 0) {
            return n;
        }

        int p[] = new int[n + 1];//'previous' cost array, horizontally
        int d[] = new int[n + 1];// cost array, horizontally
        int _d[];//placeholder to assist in swapping p and d

        // indexes into strings s and t
        int i;// iterates through s
        int j;// iterates through t

        char t_j;// jth character of t
        int cost;// cost

        for (i = 0; i <= n; i++) {
            p[i] = i;
        }

        for (j = 1; j <= m; j++) {
            t_j = t.charAt(j - 1);
            d[0] = j;

            for (i = 1; i <= n; i++) {
                cost = s.charAt(i - 1) == t_j ? 0 : 1;
                // minimum of cell to the left+1, to the top+1, diagonally left and up +cost
                d[i] = Math.min(Math.min(d[i - 1] + 1, p[i] + 1), p[i - 1] + cost);
            }

            // copy current distance counts to 'previous row' distance counts
            _d = p;
            p = d;
            d = _d;
        }

        // our last action in the above loop was to switch d and p, so p now
        // actually has the most recent cost counts
        return p[n];
    }

    public static String cutIfNecessary(String subject) {
        return subject.length() > MAX_LENGTH
                ? subject.substring(0, MAX_LENGTH) + MAX_LENGTH_SUFFIX
                : subject;
    }

    public static boolean isEmpty(String text) {
        return text == null || text.trim().length() == 0;
    }

    public static String escapeHtml(String text) {
        return Replacers.replaceAll(text, escapeHtmlReplacers);
    }

    public static String unescapeSql(String text) {
        return Replacers.replaceAll(text, unescapeSqlReplacsers);
    }
}
